Introduction to DMN Evaluation Highlights
Co-authored by Jozef Marko
In this blog post, we delve into the new DMN Evaluation Highlights feature, a valuable tool for those working extensively with Decision Model and Notation (DMN). This feature aims to enhance the evaluation process of DMN models by providing real-time insights into the decision-making process.
DMN Evaluation Highlights introduces several UI components, including a new toggle button in the overlays panel or expression editor and various indicators to show the status of the evaluation visible both in the expression editor and on the diagram nodes. These indicators help users understand whether the evaluation was successful, skipped, or unsuccessful due to errors.
To utilize this feature, users must have DMN extended services up and running. The 'Enable Evaluation Highlights' button in the diagram editor must be activated to turn on the feature. It's essential to note that the indicators in the diagram editor only appear when the feature is activated, while the expression editor shows the indicator regardless of the feature's status.
In the following sections, we will explore the different indicators and their meanings, as well as demonstrate the feature using DMN models.
Understanding DMN Evaluation Highlights
DMN (Decision Model and Notation) evaluation highlights is a new feature designed to enhance the evaluation process of DMN models. This feature aims to provide real-time insights into the evaluation of DMN models, making it easier for developers to understand and navigate complex decision tables and expressions.
To utilize this feature, users must have DMN extended services up and running. Once activated, the evaluation highlights can be turned on or off via the 'enable evaluation highlights' toggle button in the overlays panel.
The evaluation highlights introduce new UI components, such as a toggle button in the overlays panel and indicators in the node directory. These indicators signal the success or failure of the evaluation and the number of times an expression part was evaluated.
When evaluating a DMN model, numbers (0, 1, or greater) indicate the number of times a particular row was hit during the evaluation.
A checkmark signifies successful evaluation with all required inputs provided, while a cross indicates an unsuccessful evaluation due to errors. A bent arrow implies that the evaluation was skipped because necessary inputs were missing.
This feature supports nested expressions, allowing developers to evaluate complex models with multiple decision tables and conditional expressions. However, it is essential to note that evaluation highlights are currently only available in the new DMN canvas and not in the older legacy editor.
Nested Expressions and Complex Models
When working with complex DMN models that include nested expressions, such as conditional expressions, evaluation highlights prove to be incredibly useful. This feature allows you to track the evaluation of each expression in real-time, providing valuable insights into how your model processes inputs and makes decisions.
With nested expressions, the evaluation highlights will display indicating the frequency that the specific expression or decision node was hit during the evaluation. This is particularly helpful when dealing with intricate models, as it enables developers to quickly identify which parts of the model were executed and which were not.
For instance, consider a complex model with multiple decision tables and conditional tables. If you input data that triggers those tables, the evaluation highlights will show the number indicating how often that table or condition was evaluated during the process.